Color television



1943- B. T. HEWSON 2,328,145

COLOR TELEVISION Filed Aug. 20, 1941 jerh'arn 1 m Haw/Son INVEN TOE,

Patented Aug. 31, 1943 COLOR TELEVISION Bertram Tom Hewson, London, England Application August 20, 1941, Serial No. 407,537 In Great Britain June 15, 1939' 1 Claim.

In my co-pending patent applications Serial Nos. 360,352, 360,353 and 360,354, I have described and claimed certain methods of producing colored images which are applicable to color television. The present invention is concerned with certain modifications of the methods of color television described in my said co-pending patent application, and has for its chief object to provide a simple system of color television.

According to the principal feature of the present invention, an independent scanning beam is used for each of the color elements which it is desired to reproduce in the viewed image.

Over the image plate of the usual electron vcamera is disposed a multi-colour mosaic line screen between which and the line plate is arranged a mica plate or like insulating element. Instead of a single line plate, as is usual in monochromatic television, a multi-line plate is provided, each of the line sections corresponding to one of the colors of the system.

In order that this invention may be the more clearly understood and readily carried into eiiect, I will proceed to describe the same with reference to the accompanying drawing, which illustrates by way of example certain embodiments of this invention, and in which:

Figure 1 is a diagrammatic view of part of the transmitting apparatus according to the present invention as applied to a four-color system,

Figure 2 is an enlarged section through the image plate shown in Figure 1.

Figure 3 is a diagrammatic view illustrating one method of producing a multi-section line plate for use in the apparatus shown in Figure 1.

Figure 4 illustrates part of a receiving apparatus according to the present invention adapted for direct viewing, and

Figure 5 illustrates a similar apparatus by means of which the image may be projected on to a screen.

Referring now to the drawing, it will be seen that for the sake of clarity the actual amplifying, transmitting and receiving apparatus has not been shown in the drawing. Such apparatus may follow standard practice and detailed description of the same is deemed to be unnecessary.

The drawing indicates the present invention as applied to a four-color system of television and the electron camera (Figure .1) is provided with four independent scanning beams shown in broken lines provided by four independent cathodes shown diagrammatically at H, l2, l3 and I4.

Over thediiiage plate is disposed a four-color line screen which consists of' a transparent plate I 5, a mica plate or the like It and a mosaic metal coating II arranged between said transparent plate l5 and said mica plate I6. Instead of a single line plate, as is usual in monochromatic television, a four-line plate I8 is provided, each line extending from side to side of the surface and the lines being correlated with the lines of vthe mosaic color line screen so that each of the line sections corresponds to one of the colors (see Figure '2).

A multiple line plate I8, as above described, may be formed of the appropriate number of sheets of tin foil 20 appropriately insulated from one another and folded backwards and forwards, as shown in Figure 3. The folds are pressed together and clamped edgewise against the mica plate IS in register with the mosaic screen. Alternatively, the same may be produced photographically, or in any other desired manner. Each of the line sections of the plate [8 is fed to'a separate amplifier and modulator or transmitter by means of the independent lines 2|, 22, 23 and 24 so that the individual color impulses may be selectively transmitted by the transmitter and received at the receiver. 1

A similar arrangement is used at the receiver (see Figures 4 and 5), the individual cathode ray beams 30,. shown in broken lines and provided by individual cathodes, being modulated in accordance with modulation effected for the individual colors of the image at the transmitter in the usual way. The imageat the receiver may be viewed directly on the fluorescent screen 29 without the aid of auxiliary light, as shown in Figure 4, in which the lens unit 3! may, if desired, be omitted. Alternatively, an auxiliary light from a source 32 may be passed through the mosaic color line screen, as shown in Figure 5. The mosaic screensused at the transmitter and receiver are, of course, identical and suitably positioned relative to the image-receivingscreen in both cases and, accordingly, like references have been used in Figures 4 and 5 to indicate the parts corresponding to those shown in Fig-- ure 1.

At the transmitter, the color line screen acts in eo-operation'with the colored image of the object or scene being televised'in the same way as in color photography-or cinematography to filter out the colors. Thus green light from the object or scene will be stopped by the red line of the screen (if it be complementarily colored), and no image will be thrown on to the particular line of the line plate 18 at this point. There will thus be no modulation of the corresponding transmitted frequency. At the receiver, the color line screen acts in the same way as a similar device in a like system of color cinematography.

I claim:

A multi-color television system, comprising a transmitter and a receiver, each having means for using an independent individually controlled scanning beam for each of the separate colors 10 of the system, image plates at the transmitter and the receiver including like multi-color m0- saic line screens, a multi-element line plate at the transmitter, said multi-element line plate having one element for each color, and an auxiliary source of light at the receiver to pass light through the mosaic line screen at the receiver in order to render the image visible.

BERTRAM TOM HEWSON. 

